With the emerging and prosperous development of network information and various communication technology developments in wire and wireless systems, people are increasingly demanding for more network application services and the network service becomes an indispensable service in human’s daily life. With the consecutive introduction of the standards of WiMAX (IEEE 802.16e) and Long Term Evolution (LTE) systems, they will provide the users with higher speed, better service quality.
In this dissertation it will study and discuss the next generation mobile communication systems and their capabilities of providing better system efficiency. It consists of three parts in this dissertation, in the first and second parts we will study the optical fiber networks in backbone and then in part 3 we will discuss pilot design in the mobile wireless communications.
In Part one, Code-division multiple access (CDMA) technology plays an important role in the development of backbone. It possess in CDMA the characteristic better than other techniques such as it has the advantages of providing wide transmission bandwidth, effectively solving the interference and multipath fading problems in mobile wireless communications. The combination of CDMA and the fiber optical communication can enhance the advantages of both techniques.
In the synchronous frame design of the conventional synchronous transmission system, it always assumes that at the receiver end it will receive the same amount of powers from all users, i.e. it assumes that the interference powers of mutual interferences among users are constant, however in actual communication environment, the distance between each user and the receiver is different and this distance difference affects the signal strength received at the optical coupler, it needs in the design of system structure to consider the actual variation in the receiving signal strength so as to have the system structure to meet the actual communication environment. We introduce in the first part the design of a system structure to generate synchronous frames at the receiving end so as to increase the system efficiency.
In Part two, due to it provides the advantages of wide bandwidth and low loss in the fiber optical, the utilization of optical fiber will be the choice for the future transmission medium to provide wide transmission bandwidth and various kinds of services. The maturity of the optical fiber network technology has increased the developments of various optical fiber devices, the prices reduction in the optical amplifiers and laser sources etc. have promoted the wide usage of optical fiber networks. In the laser devices development it is an important issue to have the laser device to provide a stable and wideband wavelength because a stable wavelength can provide more wavelengths to users and enables the increase in the network or system efficiency, stability so that it can meet the requirements of providing high mobility and high data transmission rate in the network. In the Part two of this dissertation we will study the stability of laser sources so as to meet the network requirements of high mobility and high data transmission rate in the network.
In Part three, in the Next Generation mobile communication system, it will provide the users in outdoor and moving environment with the same or better service qualities as the indoor users. When a user is in the moving and outdoor environment, his signal will suffer the fading and noise effects when it transmits through the channel, these effects including the Shadowing Fading as the signal encounters the blocking obstructions, the Doppler Effect due to fast moving and the Fast Fading due to the multipath effect, the Co-channel Interference (CCI) and the Other-cell Interference (OCI) generating from using the same channel frequency in the transmission between the base station and the mobile station, and consequently the receiving signal quality will be affected by these adverse effects. We will in Part three recommends the design of several pilot signals and measures to solve interference issue so as to provide better system performance when signal passes through the channel suffering the above-mentioned fading and noise effects.